[jQuery] Var in the Succes: part of Ajax

[Kilhom]

Hi everyone !
My problem is simple.
Here is my code :

function ajax_test(){


        anc_pv = $('.pv_act').attr("pv");

        $.ajax({
          type: "GET",
          url: "ajax_test.php",
          data: "",
          dataType: "html",
          success: function(data){


                alert(anc_pv); // But it show "undefinided"

          }

        });
};

Any idea, someone ?
Thanks in advance ! Bye !